Leonardo da Vinci - Kathleen Krull [20]
Leonardo pooh-poohed both hypotheses—such opinions “cannot exist in a brain of much reason.” From his direct observation of shells and fossilized seaweed during walks in the Italian Alps, he came up with a third theory, one that is closer to the modern one. Shell fossils were once living organisms that had been buried at a time before the mountains were formed: “Where there is now raised land, there was once ocean.” To Leonardo, as to modern paleon tologists, fossils indicated that the history of the earth extended far beyond human records (such as the Bible)—“things are much more ancient than letters.” Such theories would have offended a strict religious sensibility, as would his scrutiny of Bible passages for lack of scientific logic.
One day Leonardo wrote, “The sun does not move,” in large letters on a page all by itself. We don’t know exactly what he meant by this. He wasn’t sure—he contradicted himself elsewhere in the notebooks. But was he beginning to question Ptolemy’s ancient and still-popular view that the sun moved around the earth?
The notebooks covered a wealth of miscellaneous offerings—whatever interested Leonardo’s butterfly mind. He tried to come up with a formula for making a synthetic material, something like plastic. It combined saffron, poppy dust, and whole lilies boiled together with eggs and glue.
Numerous themes, however, recur over and over: for example, the manipulation of nature through technology. The pages detailed all sorts of machines he designed with gears, cogwheels, screws, and pulleys. He invented a bicycle that would have really worked. He borrowed freely from what others were doing at the time (as he did in all fields), but never without questioning the work or trying to improve it. Machines of all sorts fascinated him. In fact, Leonardo viewed the human body as a machine—the ultimate machine—capable of being understood by looking at its different parts.
Leonardo wanted to find new sources of energy. In an era when the main source of power was muscle (of men and horses), he looked at new ways of using water, wind, and steam. He constructed a device to measure the volume of steam coming off a certain quantity of boiling water. Some think he anticipated the invention of the steam engine hundreds of years later; at the very least, he understood the concept of steam as power. He also proposed using solar energy, trapped by mirrors he invented, to help out the textile industry.
And, of course, there was mastery of the air, his favorite and most obsessive dream. His notebooks played endlessly with this theme. He drew parachutes, gliders made from silk and reeds, wings with all combinations of strings and pulleys, and even a sort of helicopter with a whirling spiral of fabric above it. He puzzled about the best shape—should the flying object be a butterfly with four wings, a canoe with attachments, or more like a windmill’s sails? Whatever the shape, his flying devices anticipated sophisticated principles of aerodynamics, the branch of physics having to do with motion of the air.
His ideas were the results of years of observing birds and sketching them. “The bird is an instrument operating through mathematical laws,” he believed—laws that could be figured out and applied to human flight. “As much pressure is exerted by the object against the air as by the air against the body,” he wrote—a startling observation not fully developed until Isaac Newton in the seventeenth century. He observed bats and flies equally, and was a great admirer of the aerial techniques of bees. He borrowed ideas from everyone before him who had ever contemplated flying.
Historians agree that his contraptions were probably not technically workable, but they disagree as to whether he actually made or tested any flying machine himself. If he did, we have no record of it.
Leonardo wasn’t always right. For example, he was intrigued by the study of physiognomy, the “science” of evaluating a person’s character by his or her facial features. Like everyone in his time, he believed